The long-term goal is to elucidate the mechanisms by which amino acids and various other substances are transported into and out of the lens and across the blood-aqueous and blood-vitreous barriers and how the aberrations in these mechanisms contribute to the pathogenesis of cataract and other ocular abnormalities. There is an intimate relationship tying together many of the specific areas of investigation concerned with transport insofar as the supply of amino acid and other nutrients to the interior of the eye depends not only on the movement between blood intraocular fluids but on transport mechanisms across the structural surface membranes. The studies deal with the metabolism of glutathione in the lens and ciliary body and its relation to amino acid and cation transport and to the aggregation of lens proteins. Other aspects of the study are concerned with the role of protein-bound glutathione in the lens, amino acid transport in the retina and pigment epithelium, membrane function of myoinositol in the lens, biochemical changes associated with tryptophan deficiency and X-ray-induced cataract. A major effort is also planned to establish a number of biochemical parameters including the levels of free amino acids, glutathione and the enzymes of its metabolism in normal human lens and to assess the changes in these parameters with age and in senile cataract. While many of these studies bear directly on the etiology of cataract, the investigations on blood-aqueous and blood-vitreous barriers are of potential relevance to intraocular fluid dynamics and thus glaucoma.